The present invention relates to structure of a platen on which a grooved section for receiving oversprayed ink is formed and of an inkjet recording apparatus having that platen.
Conventional structure of an inkjet recording apparatus features:
a recording head having a plural array of nozzle, positioned on the plane facing a recording medium such as a printing sheet, to jet ink onto the recording medium,
a platen to define the position of the recording medium in relation to the recording head, and for supporting the recording medium from beneath,
a control section to control the recording head, and in particular, to control the scanning movement of the recording head, as well as to control the injection of inkjet, and
a conveyance device to transport the recording medium.
That is, recording onto the recording medium is achieved by ink ejected from the nozzle arrays under the condition that the recording medium is supported on the surface of the plane platen facing the recording head.
Concerning the structure of the inkjet recording apparatus which can produce a borderless print having no white margins, that is, a print without a border on the recording medium, there is structure wherein an grooved section is formed on the surface of the platen (see Japanese Patent document 1)
Japanese patent document 1 TOKKAIHEI 2000-289275, (paragraphs [0022]-[0027], [0029]-[0039], and FIG. 4).
FIG. 9 is a sectional view showing the structure of conventional inkjet recording apparatus wherein an grooved section is formed on the surface of the platen.
As shown in FIG. 9(a), the structure of the present inkjet recording apparatus is composed of platen 2, conveyance device 4 installed to transport the recording medium on the surface of platen 2, and recording head 3 to let an ink to the surface of the recording medium.
Further, in the surface of platen 2 facing recording head 3, grooved section 21 is formed based on the position of recording head 3. In order to make a borderless print on a leading edge of the recording medium, grooved section 21 is positively formed on the surface of platen 2, and is formed at the area corresponding to at least the scanning range of recording head 3. When a print without a white margin is made on the recording medium without formation of grooved section 21, ink is ejected and sprayed beyond the edge of the recording medium, being printed on the surface of platen 2, whereupon the back surface of the recording medium comes into contact with ink, resulting in a stained back surface of the recording medium. Accordingly, by forming grooved section 21 in the surface of platen 2 and throwing the ink in grooved section 21 as shown in FIG. 9(a), ink spots on the surface of platen 2 and the back surface of the recording medium are greatly reduced.
However, there have been the following problems in conventional inkjet recording apparatus.
In cases that the end of the recording medium passes over the grooved section, when ink is ejected onto the leading edge of the recording medium which overhangs from the upstream edge of the grooved section, as shown in FIG. 9(b), rigidity of the end of the recording medium is reduced so that a phenomenon occurs wherein the end of the recording medium drops down.
Further, in order to reduce the scanning path of the recording head, the recording head becomes large, and therefore, the grooved section is also large, resulting in the phenomenon wherein the end of the recording medium falls down in the grooved section. When the end of the recording medium falls down, the end of the recording medium enters the grooved section, causing a paper jam, and further, the position of the recording medium is not firmly supported where it faces the nozzle array so that distance (PG) between the recording head and the recording medium is not constant, resulting in deterioration of print quality. Further, there is a tendency that these problems happen frequently because of a remaining curl, especially when the recording medium is a sheet from a paper roll.
In the prevention described in the above-mentioned patent document 1, the above-mentioned falling phenomenon into the grooved section (that is, a pit) is prevented by a wire which is turned around a main body. Since the wire is installed in such a way that the recording medium is carried to a sloping section which is formed on the end face in the recording medium feeding direction on the grooved section, but even though the falling phenomenon into the grooved section is prevented, distance (PG) between the recording head and the recording medium does not remain constant.